Class suggestions

I am returning to WoW after about a 5 month break. I am really looking forward to getting back into the game.

I am struggling on deciding on a class to play. When I played before I had a bunch of different classes that I would play and it ended up that I would have a bunch of characters instead of one focused character. I am hoping to decide on a class to play so that I can concentrate mainly on that class.

I enjoy healing every once in a while and doing pve every so often, but am more of pvp player. It should also be noted that I don't have many buddies that play the game, so I would want something that would be fun to play semi-alone.

I was thinking either warlock, mage, rogue, druid, monk or priest. Should I be looking for something that has more survive-ability and less damage or something that is a little more squishy and does a lot of damage?